Effects of mineral oil on the rheological behavior of polystyrene melts

The effects of mineral oil on the small strain rheological functions of polystyrene are shown to be simply related to the oil content and the rheological behavior for the neat material. Reduced variables, which are analogous to the effects of temperature, are found to successfully reduce the data for all levels of oil. The use and form of these reduced variables are shown to be predicted by the model of Bersted, which relates the rheological functions directly to the molecular weight distribution. The effects of the oil are argued to suggest that the mineral oil acts as a plasticizer for polystyrene.